Re: [PATCH] Sysctl interface to UNIX_INFLIGHT_TRIGGER_GC v.3

[David Miller <davem@davemloft.net>]

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Fri, 10 Dec 2010 14:04:33 +0100

> Le vendredi 10 décembre 2010 à 15:48 +0300, Pavel Vasilyev a écrit :
>> On 10.12.2010 06:45, Shan Wei wrote:
>> > Pavel Vasilyev wrote, at 12/10/2010 01:26 AM:
>> >> Sysctl interface to UNIX_INFLIGHT_TRIGGER_GC.
>> >> IMHO convenient for testing.
>> >>
>> >> +inflight_trigger_gc - INTEGER
>> >> +	The maximal number of inflight sockets for force garbage collect.
>> >> +
>> >> +	Default: 16000
>> > 
>> > 1) For lower payload and enough memory, it's not necessary to force garbage collection.
>> > So set it to 0, disable gc.
>> 
>> 
>> May be, set default to 2000, and zero to disable
>> 
> 
> zero to disable ?
> 
> Maybe you missed commit 9915672d41273f5b77 intent.
> 
> If you have no limit (like old kernels), you can freeze your machine,
> even if it has terabytes of ram, running a single program, even as a non
> root user.
> 
> When we discussed about the fix, we said a limit was needed, obviously.
> 
> Now you'll have to prove we need to make it a sysctl (yet
> another /proc/sys/net parameter, yet another documentation to add...)
> 
> Even changing default from 16000 to 2000 must be for a valid reason (a
> real use case)

I don't want to add this sysctl.  Exactly because there is no reason
to believe that the current value could even need to be changed by
anyone.

Once a demonstratable need can be proven and shown beyond a shadow
of a doubt, we can consider adding the sysctl.

We have too many damn sysctls as-is.